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Date: Tue, 5 May 2015 11:07:06 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Jiri Olsa <jolsa@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
        David Ahern <dsahern@gmail.com>, Joonsoo Kim <js1304@gmail.com>,
        Minchan Kim <minchan@kernel.org>, Pekka Enberg <penberg@kernel.org>,
        linux-mm@kvack.org
Subject: Re: [PATCH v2] perf kmem: Show warning when trying to run stat
 without record
Message-ID: <20150505140706.GJ10475@kernel.org>
References: <20150504161539.GG10475@kernel.org>
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Em Tue, May 05, 2015 at 09:58:12AM +0900, Namhyung Kim escreveu:
> Sometimes one can mistakenly run perf kmem stat without perf kmem
> record before or different configuration like recoding --slab and stat
> --page.  Show a warning message like below to inform user:
> 
>   # perf kmem stat --page --caller
>   Not found page events.  Have you run 'perf kmem record --page' before?
> 
> Acked-by: Pekka Enberg <penberg@kernel.org>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Thanks, applied.

I just found the messages a bit odd souding, perhaps:

   # perf kmem stat --page --caller
   No page allocation events found.  Have you run 'perf kmem record --page'?

Pekka?

- Arnaldo

> ---
> Use perf_evlist__find_tracepoint_by_name().
> 
>  tools/perf/builtin-kmem.c | 17 ++++++++++++++---
>  1 file changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/builtin-kmem.c b/tools/perf/builtin-kmem.c
> index 828b7284e547..5868b4347925 100644
> --- a/tools/perf/builtin-kmem.c
> +++ b/tools/perf/builtin-kmem.c
> @@ -1882,6 +1882,7 @@ int cmd_kmem(int argc, const char **argv, const char *prefix __maybe_unused)
>  	};
>  	struct perf_session *session;
>  	int ret = -1;
> +	const char errmsg[] = "Not found %s events.  Have you run 'perf kmem record --%s' before?\n";
>  
>  	perf_config(kmem_config, NULL);
>  	argc = parse_options_subcommand(argc, argv, kmem_options,
> @@ -1908,11 +1909,21 @@ int cmd_kmem(int argc, const char **argv, const char *prefix __maybe_unused)
>  	if (session == NULL)
>  		return -1;
>  
> +	if (kmem_slab) {
> +		if (!perf_evlist__find_tracepoint_by_name(session->evlist,
> +							  "kmem:kmalloc")) {
> +			pr_err(errmsg, "slab", "slab");
> +			return -1;
> +		}
> +	}
> +
>  	if (kmem_page) {
> -		struct perf_evsel *evsel = perf_evlist__first(session->evlist);
> +		struct perf_evsel *evsel;
>  
> -		if (evsel == NULL || evsel->tp_format == NULL) {
> -			pr_err("invalid event found.. aborting\n");
> +		evsel = perf_evlist__find_tracepoint_by_name(session->evlist,
> +							     "kmem:mm_page_alloc");
> +		if (evsel == NULL) {
> +			pr_err(errmsg, "page", "page");
>  			return -1;
>  		}
>  
> -- 
> 2.3.7